Tire valve insert

ABSTRACT

A tire valve insert manufactured from a cylindrical metal tube by axially compressing the tube to form a peripheral flange, radially expanding the tube, forming internal tapers, and threading various internal as well as external sections of said tube.

llnile if? States Pa ten l Inventor ,llames 1F. Scherer 2 Wail-Jo Trail, Milford, Ohio 45150 Appl. No. 40,6911

Filed May 26, 1970 Patented Dec. M, 1971 Continuation-impart all application Ser. No. 821,858, May 5, 1969, now abandoned. This application May 26, 11970, Ser. No. 40,691

Tum VALVE INSERT 13 Claims, 24 Drawing Figs.

137/223, 137/234.5 lint. Cl F1611 15/20 Field all Search 137/223,

[56] References (Iliad UNITED STATES PATENTS 1,761,487 6/1930 Oakley 137/223 X 2,284,971 6/1942 Broecker... 137/223 2,309,430 1/1943 Albert 137/223 3,513,885 5/1970 Horwitt 137/223 X Primary Examiner-Harold W. Weakley Attorney-Wood, Herron & Evans ABSTRACT: A tire valve insert manufactured from a cylindrical metal tube by axially compressing the tube to form a peripheral flange, radially expanding the tube, forming internal tapers, and threading various intezrnal as well as external sections ofsaid tube.

PATENTEMEMM 3,6272% sum 10F 4 INVENTQR.

FATENTEUUEBMISYI 3,6272% SHEET 2 OF d INVENTUR. w. M

'llllWlE VALVE IINSEHRT This application is a continuation-impart of my copending application Ser. No. 821,858, now abandoned. That application in turn is a division of application Ser. No. 394,382, filed Aug. 31, 1964 for Method of Melting Tire Valve Inserts," now US. Pat. No. 3,441,997. Application Ser. No. 394,382 was in turn a continuation-in-part of application Ser. No. 387,070, filed Aug. 3, 1964, now abandoned.

This invention relates to pneumatic valve stem assemblies and particularly to the inserts which go to make up such assemblies. "Insert" is a term used in the tire industry to denote the external sleeve which surrounds the operating parts of the valve or the so-called valve core.

Inserts of pneumatic valves for use in tubeless tires are conventionally and commercially made upon an automatic screw machine. These machines are very high speed and are capable of manufacturing thousands of pieces per hour from solid bar stock. However, an inherent limitation of the machining process is the waste which accompanies it. Percentagewise, a large amount of starting material ends up as scrap metal which can be salvaged but which nonetheless increases the cost of the finished product.

It has been an objective of this invention to reduce the cost to the consumer of tubeless tire valve inserts and particularly to do so by minimizing the amount of scrap metal produced during the production of the part. This objective has been accomplished by this invention by forming the complete metal insert from a piece of tubular bar stock rather than by machining it from solid bar stock. The advantage of manufacturing the insert by this method is that it substantially reduces the scrap and thus the ultimate cost of the part. In fact, this method reduces the cost of the material from which the part is made by as much as 30 percent over the method practiced commercially for producing the millions of inserts used in the automobile industry today.

inserts for tubeless tires conventionally consist of three different diameter sections; a large diameter end, an intermediate diameter middle section, and a small diameter end. The large diameter end has internal threads for the reception of a threaded section of the tire valve core and external threads for reception of the conventional dust cap. Connecting the large threaded end and the smaller diameter intermediate section is an internally tapered valve seat. Surrounding this valve seat is a heavy external flange having a flat upper surface adapted to be seated upon a mold surface when a rubber sleeve is molded around the insert.

During the era of tires having inner tubes, it was proposed that tire valve inserts be made from tube or sheet metal. However, no one has been able to economically accomplish that end since the advent of the tubeless tire. The primary reason that no one has been able to do so has been because the old methods by means of which tube-type inserts were made from sheet metal are no longer practical with tubeless-type tire valve inserts. Specifically, the old tube-type inserts were made by either drawing a sleeve to the proper configuration by a series of drawing operations or they were configurated by reducing the diameter of various sections of a large tube so as to bring it to the proper configuration. Neither of these approaches is practical with a tubeless-type tire valve insert.

The old approach to forming tire valve inserts from sheet metal by drawing the tube to its various configurations is impossible with tubeless-type inserts because of the length-todiameter ratio of the inserts used in modern tubeless tires..

As for the use of reducing techniques to form the tubelesstype inserts, this is impractical because of the fins which result from this type of forming as well as because of the uncontrolled change of length of the tube which results. If the tapered valve seat were formed by crimping a larger diameter tube, the tapered section would have an internal and external fin, the internal fin being in the nature of a depression in the area where the tube-crimping dies meet. Such a depression would be completely unsatisfactory if the tapered area is to serve as a sealed valve seat and could only be eliminated by a machining operation. If machined, the wall thickness would in all probability be too thin for a satisfactory insert.

l have discovered that tubeless-type tire valve inserts may be made from tubes of generally uniform diameter and wall thickness by a series of expanding operations. ln other words, a satisfactory tubeless tire valve insert may be made with its attendant savinw in material and cost of production by expanding a small diameter tube rather than by the old conventional method of crimping or reducing in diameter a large diameter tube to configure it.

One of the advantages of expanding the tube rather than reducing it in diameter to form a properly configurated sleeve or insert is that this may be accomplished on a punch press. As is well ltnown, punch presses operate at speeds approximately twice that of screw machines. This results in a savings of both labor and capital.

Another advantage of this method of producing tire valve inserts is that it results in the production of a new and novel insert'which is less expensive than an insert produced by the screw machine method. It also has the advantage that it may be substituted in a conventional automobile tire valve core assembly for a standard screw machine produced insert without any modification of the core assembly.

These and other objects and advantages of this invention will be more readily apparent from. a description of the drawings in which:

FIG. l is a perspective view of a conventional pneumatic tire incorporating a tire valve insert of the type produced by this invention,

FIG. 2 is a cross-sectional view taken along the line 2-2 of H6. 1 with the tire valve core being shown in phantom,

FIG. 3 is a sleeve of the type from which the insert of FIG. 2 is made,

FIGS. 4 through 14 illustrate diagrammatically the various forming operations in practicing the method of this invention,

FlGS. 15 through 118 illustrate alternative small-end configurations of the inserts and the method for producing those ends,

FIGS. 19 and 20 illustrate diagrammatically the final threading of the completely formed or shaped insert,

FIGS. 21 through 23 illustrate diagrammatically alternative forming operations which may be used in the practice of my invention as a substitute for the forming operation illustrated in FIGS. 8 and 9 to produce a modification of my tire valve insert,

F I0. 24 is a cross-sectional view similar to F IG. 2 of the tire valve subassembly but illustrating the completed insert which results from the alternative forming operations illustrated in FIGS. 2ll-23.

Referring to FlG. 2, it will be seen that the finished product manufactured by practicing this invention has a large externally threaded end section 10 beneath which it is slightly reduced in diameter and internally threaded on a section designated by the numeral ll. Beneath this internally threaded section it is an external flange or rib 112 which serves to locate the insert in a tire mold. Beneath this flange is a tapered valve seat section 113. The tapered section ends in a small diameter section M beneath which the sleeve is bulged at T5 for the middle section of the valve insert. The bulged section ends in a small diameter end section 116 which serves as a washer or spring seat as is more fully explained hereinafter.

In use, this sleeve or insert 5 becomes the center section of a molded rubber subassembly. The molded rubber 6 forms a sleeve around the insert and it is this sleeve 6 which is placed in the metal wheels of a tubeless tire.

The rib 12 serves as a seating surface when the molded rubber sleeve 6 is molded around the insert. As may be seen most clearly in MG. 2, the upper surface of the rib is flat and forms a corner with the exterior of the internally threaded section ill. During the rubber-molding operation, a pin (not shown) is inserted into the smaller diameter section 16 so as to seal this end of the insert against the ingress of rubber. This pin has a shoulder which rests against the small end of the insert and forces the top surface of the rib 112 into tight engagement with the mold so as to preclude rubber escaping from the mold and forming flash around the exterior of the threaded section 11. Because of the axial force applied to the rib 12 during the molding operation, it is made of double thickness tubing.

The tire valve is completed by a core indicated generally by the numeral and shown in phantom in FIG. 2. Since the core forms no part of this invention and is only described and shown herein in order to illustrate the function of the various sections and configurations of the insert, it will be only briefly described. Essentially, it consists of a center pin 21 having bulbous sections at each end. Intermediate the ends of the center pin are a pair of sleeves 22, 23 secured to the pin so as to hold a rubber seal 24 between them. A washer or shoe 25 is slidably mounted over the lower end of the center pin with its lowermost end 26 resting against the small-end section 16 of the insert. Between the shoe and the bottom of the sleeve 22 is a compression spring 28 which biases the center pin into a closed position. A brass sleeve 30 surrounds the upper end of the center pin. This sleeve has external threads 31 threaded into the internal threads 32 of the insert or valve stem. When the core is initially assembled into the valve, this threaded upper end section is screwed down into the internally threaded section of the core until a Teflon sleeve 33 seats upon the internally tapered section 13 of the insert. When the Teflon sleeve is seated upon the tapered section, the lower end 34 of the brass sleeve 30 rests against the upper surface of the rubber seal 24 so as to form a pneumatic seal with that gasket.

When the center pin 21 is pushed downwardly against the bias of the spring 28, an area between the lower end 34 of the brass sleeve and the gasket 24 opens so as to permit air to pass either into or out of the interior bore 36 of the sleeve 30, via the gap between the sleeve 30 and the gasket 24, through the lower section of the bore of the insert, and through apertures (not shown) in the washer or shoe 25 to or from the interior of the tire.

Referring now to FIG. 3, it will be seen that the tire valve insert 5 is made from a section of brass tubing indicated generally by the numeral 7. This section of tubing 7 is cut to proper length from tubular bar stock. Thereafter, the tubing 7 is formed into a completed insert as shown in FIG. 2 upon an automatic-indexed table punch press or a shuttle rail press in which the part is indexed between stations automatically until the tube has been completely formed. Thereafter, the configurated tube is transferred to a tapping machine which places the internal threads 32 and the external threads 40 on the completed insert. Since neither the punch press nor the transfer mechanism form any part of this invention and would only serve to unnecessarily complicate the drawings, they have not been illustrated.

The first step in the production of the insert is to locate the tubular sleeve 7 between a pair of male punches or dies 50, 51, each of which is surrounded by steel sleeves 52, 53 respectively. The sleeves 52, 53 are spaced from the punches 50, 51 slightly more than the thickness of the tubular sleeve 7 so that the tube 7 may enter between the punches and the sleeves. Punch 50 is slightly larger than the initial bore of the tube 7 so that as the tapered end 54 of punch 50 enters the upper end of the tube, it opens or enlarges the end 55. It should be noted that the punch 50 is slightly longer than the sleeve 52 so that a gap occurs between the flat end 56 of the sleeve 52 and the curved upper end 57 of the sleeve 53. This gap permits the metal of the brass sleeve 7 to flow outwardly between the sleeves 52, 53 so as to form a double thickness rib 12 onthe periphery of the tube. Simultaneous with the forming of the rib, the upper end 55 of the sleeve is cold-headed or axially compressed so as to increase the wall thickness of this section of the tube. The rib 12 is formed and the wall thickness of the upper section 55 of the tube is increased when the bottom 59 of an upper die engages the upper end of the tube so as to push the upper end of the tube downwardly. In so doing, it forces the upper end of the tube to compress to the dimension between the sleeve 52 and the punch 50 which is slightly greater than that of the starting tube wall thickness. In one preferred embodiment of the invention, the internal diameter of the upper end of the tube is increased from a 0.156 inch to approximately 0.168 inch during the step of forming the rib 58 on the tube and the wall thickness is increased from 0.032 inch to 0.045 inch.

The next step in the forming of the tube is to further expand the diameter of the upper section 55 of the tube and to further increase the wall thickness of this section. In a preferred embodiment, this diameter is expanded from 0.168 inch to 0.180 inch during this second step as the wall thickness is increased to 0.050 inch. This is accomplished by a second punch 60 having a tapered end 61. The punch 60 is surrounded by a sleeve 62 so that the wall thickness of the upper section 55 may be further increased by a cold-heading operation when the bottom 63 of the upper die engages the upper end of the tube 7. During this operation, the lower end of the tube is reinforced by either the same punch SI and sleeve 53 used in the first operation or a similarly dimensioned punch and sleeve.

After the punches 51, 60 and the surrounding supporting sleeves 53, 62 are removed (FIG. 6), the lower end 65 of the tube 7 is bulged by a male die or punch. In the preferred embodiment, this male die expands the lower end of the tube from its original diameter of 0.156 inch to 0.170 inch. After the lower end of the tube has been sized or expanded by the die 66, the underside of the rib 12 is engaged by a pair of stripper plates or a cushion knockout (not shown) which holds the tube 7 and enables the punch 66 to be pulled (FIG. 8)

from the tube.

The next step in the production of the insert (FIG. 9) is to open or increase the internal diameter of the upper portion 70 of top section 55 while simultaneously rough-forming the tapered valve seat section 13. To this end, a male die 71 is inserted through the top of the tube. This die has a lower tapered end 72, a cylindrical middle section 73 and an enlarged cylindrical upper end section 74 joined to the middle section by a tapered section 75. As this male punch or die 71 is inserted into the tube, the tapered end section 72 of the die forms a taper on the tube section 13 by bulging it outwardly while simultaneously the upper end section 74 of the die opens or expands the very top portion of the tube. In the described embodiment, the very topmost portion of the tube is expanded to 0.302 inch.

After this operation, the die 71 is removed while the insert is engaged by a pair of stripper plates 76 (FIG. 10).

The tube 7 then undergoes a final sizing operation by a male punch or die 78 which enters the tube and engages the tapered portion I3 to finally size this section. In the preferred embodiment, this section is tapered to a 17 angle. Thereafter, the tube is again engaged by a pair of stripper plates 79 which secure it against movement while the die 78 is removed.

The small end of the tube 65 is thereafter crimped as shown in FIGS. 11 and 12 to fonn a washer or spring engaging small diameter section I6. This is accomplished by a pair of semicylindrical discs 80 being moved laterally into engagement with the end section. Alternatively, the small end of the tube may be formed by a female die 81 being moved axially and forced over the end of the tube to form a generally tapered end section 82 as shown in FIG. 15. As still another alternative, the small end of the tube 16 may be formed by a female die 83 being moved axially over the tube to form a cylindrical small-end section (FIG. 16). As still another alternative, a pair of semicylindrical discs similar in cross-sectional configuration to those illustrated in FIG. 12 but of lesser thickness may be moved laterally into engagement with the tube to form an arcuate interior rib 84 (FIG. 17) or a flat rib 85 as illustrated in FIG. 18.

All of the forming operations should be carried out as rapidly as possible so that from the first to the last step the metal will be continuously heated as it is worked and not allowed to cool. In this way maximum malleability of the metal will be achieved.

After the complete forming of the tube as hereinabove described, internal threads 32 are placed on the end section 111 by a tap Ml (lFlG. 119) and external threads d are threaded onto the large-end section by a female tap hi (FIG.

it should be noted that during the forming of the insert, the sections llll and 111 are increased in thickness by the coldheading operations. Preferably the increase in wall thickness is at least percent during the forming of the piece. Additionally, it should be noted that the external and internal threads are not coextensive. in other words, the external threads end before the internal threads begin so that minimum thickness material may be used in the area of the threads.

Referring now to FlGS. 211-33 there is illustrated an alternative series of forming operations which may be used in the practice of this invention to generate another modification of the tire valve insert, the finished or resulting modified tire valve insert W5 being illustrated in FIG. 2d. The series of operations followed to produce the tire valve insert 1105 illustrated in F116. M1 is identical to the series of operations or method steps depicted in lFlGS. 3-20 to generate the tire valve insert 5, except that the method followed to produce the tire valve insert lltlfi depicted in FIG. 241 requires one additional step or operation. This additional step is illustrated diagrammatically in flG. 22. it results in a slightly modified insert 1105 in which the tapered valve seat of the insert is located in the same transverse plane of the valve as the flange i112. ln order to so locate the tapered valve seat, the creme 11117 generated by the folding operation depicted in F168. d and 5 must be closed so as to avoid an air leak across the tapered valve seat.

. Referring now to FIG. 21 it will be seen that the sleeve W7 is identical to the sleeve 7 depicted in H0. d of the modification illustrated in F163. 3-20. The series of operations performed upon the sleeve 1llil7 up through that stage to produce the sleeve MW of H0. 211 is identical to the series of operations depicted in FlGS. M. The one additional step required to produce the insert 1105 (F16. Ed) is depicted in H6. 22. In this step, the metal in the lower end 1115 of the sleeve and particularly the metal in the necked-in portion llllll is swaged upwardly by the die 1119. This results in the necked-in portion lid being forced upwardly over that portion of the interior of the tube which is located internally of the flange ll2. Forcing of this metal upwardly causes the crease 1117' (N65. ZZZ-2d) to be closed and to be pushed upwardly so that it opens into the upper end portion 1155 of the tube 107.

As depicted in PK}. 23, the next forming operation after removal of the die 11119 is to insert the die 117i with its tapered upper end portion 1175 and its tapered lower end portion 1172 to enlarge the upper end 1155 of the tube and to simultaneously form the tapered seat 1120 on the portion N3 of the insert located interiorly of the flange 1112. Since the tapered seat is located below the crease 1117', air cannot leak past the seat 112% via the crease 1117.

The sequence of operations required to produce the valve insert depicted in FIG. 2% from the partially formed sleeve depicted in lFlG. 23 is the same as the series of operations depicted in FIGS. ill-Ml. Consequently, since the operations are identical, they have not been shown in detail.

The resulting valve stem insert lllllfi which results from the additional swagging operation depicted in FIG. 2.2 and the location of the tapered seat 12 0 on the interior of the flange i112 is advantageous in some applications because it may be substituted without any valve stem dimensional changes for inserts now commercially being produced on automatic screw machines for the automobile tire industry. it has the advantage, though, of being much less expensive to produce than the screw machine insert for which it may be substituted.

While dimensions have been given to a preferred embodiment of the invention to facilitate an understanding of it, and while preferred embodiments of the invention have been illustrated, numerous changes and modifications of this invention will be readily apparent to those skilled in the art without departing from the spirit of the invention. Therefore, I intend only to be limited by the appended claims.

Having described my invention, l claim:

1. A tubular valve stem assembly insert made from a tubular metal sleeve of uniform wall thickness comprising,

a first section and a second section separated by a double wall thickness lateral flange on the periphery of said tube,

said first section having a tapered valve seat portion,

said second section having a small diameter portion adjacent said flange and a larger diameter portion adjacent the end of said second section,

said larger diameter portion of said second section having threads on its exterior and a smooth internal surface, and

said smaller diameter portion of said second section having a smooth external surface and threads on its interior surface. i

2. A valve stem assembly insert made from a tubular metal sleeve of uniform wall thickness comprising,

a first section and a second section separated by a double wall thickness lateral flange on the periphery of said tube,

said first section having a portion adjacent its end of small diameter than the remainder of said first section,

said first section having a tapered valve seat portion adjacent said flange,

said second section having a smaller diameter portion adjacent said flange and a larger diameter portion adjacent the end of said second section,

said larger diameter portion of saidl second section having threads on its exterior and a smooth internal surface, and

said smaller diameter portion of said second section having a smooth external surface and threads on its interior surface.

3. A tubular valve stem assembly insert made from a tubular metal sleeve ofuniform wall thickness comprising,

a first section and a second section separated by a double wall thickness lateral flange on the periphery of said tube, said first section having a tapered valve seat portion adjacent said flange,

said second section having a small diameter portion adjacent said flange and a larger diameter portion adjacent the end of said second section,

said larger diameter portion of said second section having threads on its exterior and a smooth internal surface, and

said smaller diameter portion of said second section having a smooth external surface and threads on its interior surface.

41. A tubular valve stem assembly insert made from a tubular metal sleeve of substantially uniform wall thickness comprisll1 a first cylindrical wall section and a second cylindrical wall section separated by a double wall thickness lateral flange on the periphery of said sleeve,

said first cylindrical wall section and said double wall thickness flange having a varying diameter circular cross section interior surface defining thereon a tapered valve seat portion,

said second cylindrical wall section having a small diameter portion adjacent said flange and a larger diameter portion adjacent the end of said second cylindrical wall section,

said larger diameter portion of said second wall section having threads on its exterior and a smooth internal surface, and

said smaller diameter portion of said second section having a smooth external surface and threads on its internal surface.

5. A valve stem assembly insert made from a tubular metal sleeve of substantially uniform wall thickness comprising,

a first wall section and a second wall section separated by a double wall thickness lateral flange on the periphery of said sleeve,

said first wall section and said double wall thickness flange having a varying diameter circular cross section interior surface, there being a tapered valve seat defined on said interior surface,

said second wall section having a smaller diameter wall portion adjacent said flange and a larger diameter wall portion adjacent the end of said second wall section,

said larger diameter portion of said second wall section having threads on its exterior and a smooth internal surface, and

said smaller diameter portion of said second wall section having a smooth external surface and threads on its internal surface.

6. The valve stem assembly insert of claim in which said tapered valve seat is located primarily on the interior surface of said first section adjacent the interior surface of said flange.

7. The valve stem assembly insert of claim 5 in which said tapered valve seat is located primarily on the interior surface of said double wall thickness lateral flange.

8. The valve stem assembly insert of claim 5 in which said first wall section has a portion adjacent its end of smaller diameter than the remainder of said first section.

9. A valve stem assembly insert made from a tubular metal sleeve of substantially uniform wall thickness comprising,

a first wall section and a second wall section separated by a folded double wall thickness lateral flange section, said flange section having a lateral flange extending outwardly on the periphery of said sleeve, said folded lateral flange section having a crease therein extending into the interior of said sleeve,

said first wall section and said double wall thickness flange section having a varying diameter circular cross section interior surface, there being a tapered valve seat defined on said interior surface,

said second wall section having a smaller diameter wall portion adjacent said flange and a larger diameter wall portion adjacent the end of said second wall section,

said larger diameter portion of said second wall section having threads on its exterior and a smooth internal surface, and

said smaller diameter portion of said second wall section having a smooth external surface and threads on its internal surface.

10. The valve stem assembly insert of claim 9 in which said tapered valve seat is located primarily on the interior surface of said first section adjacent the interior surface of said flange section.

11. The valve stem assembly insert of claim 9 in which said tapered valve seat is located primarily on the interior surface of said double wall thickness lateral flange section.

12. The valve stem assembly insert of claim 11 in which there is a portion of said first wall section swaged over the interior of the lateral flange section so that said crease opens into the interior of said second wall section, said tapered valve seat thereby being free of said crease.

l3. A valve stem assembly insert made from a tubular metal sleeve of substantially uniform wall thickness comprising,

a first wall section and a second wall section separated by a folded double wall thickness lateral flange section, said flange section having a lateral flange extending outwardly on the periphery of said sleeve, said folded lateral flange section having a crease therein extending into the interior of said sleeve,

said first wall section and said double wall thickness flange section having a varying diameter circular cross section interior surface, there being a tapered valve seat defined on said interior surface,

said second wall section having threads on the exterior and interior surface thereof, 0

said tapered valve seat being located primarily on the interior surface of said double wall thickness lateral flange section, and

a portion of said first wall section being swaged over the interior of said lateral flange section so that said crease opens into the interior of said second wall section, said tapered valve seat thereby being free of said crease.

a a a a a 

1. A tubular valve stem assembly insert made from a tubular metal sleeve of uniform wall thickness comprising, a first section and a second section separated by a double wall thickness lateral flange on the periphery of said tube, said first section having a tapered valve seat portion, said second section having a small diameter portion adjacent said flange and a larger diameter portion adjacent the end of said second section, said larger diameter portion of said second section having threads on its exterior and a smooth internal surface, and said smaller diameter portion of said second section having a smooth external surface and threads on its interior surface.
 2. A valve stem assembly insert made from a tubular metal sleeve of uniform wall thickness comprising, a first section and a second section separated by a double wall thickness lateral flange on the periphery of said tube, said first section having a portion adjacent its end of smaller diameter than the remainder of said first section, said first section having a tapered valve seat portion adjacent said flange, said second section having a smaller diameter portion adjacent said flange and a larger diameter portion adjacent the end of said second section, said larger diameter portion of said second section having threads on its exterior and a smooth internal surface, and said smaller diameter portion of said second section having a smooth external surface and threads on its interior surface.
 3. A tubular valve stem assembly insert made from a tubular metal sleeve of Uniform wall thickness comprising, a first section and a second section separated by a double wall thickness lateral flange on the periphery of said tube, said first section having a tapered valve seat portion adjacent said flange, said second section having a small diameter portion adjacent said flange and a larger diameter portion adjacent the end of said second section, said larger diameter portion of said second section having threads on its exterior and a smooth internal surface, and said smaller diameter portion of said second section having a smooth external surface and threads on its interior surface.
 4. A tubular valve stem assembly insert made from a tubular metal sleeve of substantially uniform wall thickness comprising, a first cylindrical wall section and a second cylindrical wall section separated by a double wall thickness lateral flange on the periphery of said sleeve, said first cylindrical wall section and said double wall thickness flange having a varying diameter circular cross section interior surface defining thereon a tapered valve seat portion, said second cylindrical wall section having a small diameter portion adjacent said flange and a larger diameter portion adjacent the end of said second cylindrical wall section, said larger diameter portion of said second wall section having threads on its exterior and a smooth internal surface, and said smaller diameter portion of said second section having a smooth external surface and threads on its internal surface.
 5. A valve stem assembly insert made from a tubular metal sleeve of substantially uniform wall thickness comprising, a first wall section and a second wall section separated by a double wall thickness lateral flange on the periphery of said sleeve, said first wall section and said double wall thickness flange having a varying diameter circular cross section interior surface, there being a tapered valve seat defined on said interior surface, said second wall section having a smaller diameter wall portion adjacent said flange and a larger diameter wall portion adjacent the end of said second wall section, said larger diameter portion of said second wall section having threads on its exterior and a smooth internal surface, and said smaller diameter portion of said second wall section having a smooth external surface and threads on its internal surface.
 6. The valve stem assembly insert of claim 5 in which said tapered valve seat is located primarily on the interior surface of said first section adjacent the interior surface of said flange.
 7. The valve stem assembly insert of claim 5 in which said tapered valve seat is located primarily on the interior surface of said double wall thickness lateral flange.
 8. The valve stem assembly insert of claim 5 in which said first wall section has a portion adjacent its end of smaller diameter than the remainder of said first section.
 9. A valve stem assembly insert made from a tubular metal sleeve of substantially uniform wall thickness comprising, a first wall section and a second wall section separated by a folded double wall thickness lateral flange section, said flange section having a lateral flange extending outwardly on the periphery of said sleeve, said folded lateral flange section having a crease therein extending into the interior of said sleeve, said first wall section and said double wall thickness flange section having a varying diameter circular cross section interior surface, there being a tapered valve seat defined on said interior surface, said second wall section having a smaller diameter wall portion adjacent said flange and a larger diameter wall portion adjacent the end of said second wall section, said larger diameter portion of said second wall section having threads on its exterior and a smooth internal surface, and said smaller diameter portion of said second wall section having a smooth external surface and thReads on its internal surface.
 10. The valve stem assembly insert of claim 9 in which said tapered valve seat is located primarily on the interior surface of said first section adjacent the interior surface of said flange section.
 11. The valve stem assembly insert of claim 9 in which said tapered valve seat is located primarily on the interior surface of said double wall thickness lateral flange section.
 12. The valve stem assembly insert of claim 11 in which there is a portion of said first wall section swaged over the interior of the lateral flange section so that said crease opens into the interior of said second wall section, said tapered valve seat thereby being free of said crease.
 13. A valve stem assembly insert made from a tubular metal sleeve of substantially uniform wall thickness comprising, a first wall section and a second wall section separated by a folded double wall thickness lateral flange section, said flange section having a lateral flange extending outwardly on the periphery of said sleeve, said folded lateral flange section having a crease therein extending into the interior of said sleeve, said first wall section and said double wall thickness flange section having a varying diameter circular cross section interior surface, there being a tapered valve seat defined on said interior surface, said second wall section having threads on the exterior and interior surface thereof, said tapered valve seat being located primarily on the interior surface of said double wall thickness lateral flange section, and a portion of said first wall section being swaged over the interior of said lateral flange section so that said crease opens into the interior of said second wall section, said tapered valve seat thereby being free of said crease. 